Hi Sophie,
This is very easy to do, but then it is best to create your title animation using the Transform tool instead of doing it in the Inspector. In the Transform tool you can manually change the interpolation between the keyframes of an animation, which you cannot do in the Inspector nor in the Video animation editor.
It takes more time to explain than to show, so I have made a very quick video explaining how to do this. You can download the tutorial here:
files.me.com/ronnycourtens/10nqb2.mov
Best wishes,
Ronny